Method of producing dye images



I Patented June 15, 1943 3 2,322,001 ore or raooocnso DYE IMAGES GeorgeEhreniried, Rochester, N. Y, assignor to Eastman Kodak Company,Rochester, N. Y., a

corporation of New Jersey No Drawing. Application October lo, 194.

Serial No. 369,622

6 Claims.

This invention relates to a method for producing colored photographicimages and particularly to a method of forming colored images in imagein which a dyed gelatin layer containing a silver image is treated witha solution of a strong reducing agent such as sodium hydrosulilte orstannous chloride. The reducing bleach bath destroys the dye in thelayer selectively in the region of the silver image, giving'a positivedye image from a. negative silver image. The destruction of a dye toform a photographic image in this process appears to depend upon thecatalytic action of the silver image which results in the destruction ofthedye in that portion of the film when treated with a suitable reducingbleach bath.

I; have found that in many cases the imageiorming dyes used inthisprocess may be more (Ci. sis-s) Chechak 'U. S. patent applicationSerial No.

readily bleached if a silver salt image is used ln' 7 place of ametallic silver image and the bleaching bath is allowed to reduce thissilver salt to metallic silver in the same operation as the destructionof the dye. The silver salt image may be produced, for example, byrehalogenizing a developed and fixed'silver image. I

It is, therefore, an objeetto provide a novel method of forming acolored photographic image in a photographic layer. A-iurther object isto provide a novel method for destroying a dye uniformly dispersed in aphotographic layer under the influence of a silver salt image.

These objects are preferably accomplished according to my invention bydeveloping the emuls'ion layer containing the uniformly dispersed.

image-forming dye, fixing, washin and than rehalogenizing the silverimage thus formed and treating the layer with a suitable reducing bleachbath. I

The photographic element treated according to my invention may comprisea single emulsion of poly-azo dyes as disclosed in Christensen U. S.

; Patent 1,517,049, though not necessarily the same dyes.

If a three-layer photographic element is used for the production ofnatural color images, the three emulsion layers preferably contain dyescoupling with 2 mols of R-salt.

each of which is'r'oughly complementary in color to the effectivesensitivity of the emulsion layer. The red sensitive layer may becolored blue-green with one of the following dyes.

Eaample 1.Pontamine Fast Green 581. (Du Pont) Example 2.--A blue dye ofless suitable color, bfit of satisfactory bleaching properties, made bytetrazotizing 4,4"-diamino-2,2'-dimethyl, 5,5'-dimethoxytriphenylmethane and coupling it with two mols of chromotropic acid.

Example 3.--Indigo.

The green-sensitive magenta with one of the following dyes, some ofwhich are described in Seymour, Young, and

333,808, iiled May 7, 1940.

Example 4.-Monosol Carmine LS (Color Index Example 5.-A dye made bytetrazotizing 4,4 diamino-Zi,3'-dimethoxy diphenyl methane and Example6.The dye made by tetrazotizing 1 mol of 4,4'-diamino triphenyl methaneand coupling with 2 mols of N-lauroyl H-acid.

Example 7.-The dyes made by tetrazotizing 1 1 mol of 4,4'-diamino-3,3',6,6'.-tetramethyl triphenyl methane and coupling-with 2 mols ofN-he'ptoyl H-acicl or one of the following compounds:

Example 8.-N-lauroyl H-acid. Example 9.--N-henzoyl H mid. Example,1il.--l-naphthol-3fi-disullonicacida-p-naphthalene sulfonate.

Example Z1.--N(naphthalene B sulfonyl) H- acid.

Eroingrle l2.-hl(-henzamido henzoyl) H-acid.

Example 23.--Ciu'omotropio acid.

Example 1%.Thfi dye made by tetrazotlzing 4,4'-diam.ino2,2-dimetl1yl-5,5-dimethoxy trl= phenylmethane and coupling with .2 molsof 1-naphthol-8-para-tolyl sulionatedfi-disulionlc acid.

Example i5.---'lhe dye made by tetrazotizlng U. S. patent anplications333,8t6 and 33$,hil7, tiled May r, was.

Example i l-The dye made by tetrazotizing Pool-amine l'liaao Yellow 2G1and coupling with layer may be colored Example 19.--The dye made bytetrazotizing 4A-cliamino3,3-dimethyl-d' -"nethoxytriphenylmethane-3"-sulfonic acid and coupling with 2 mols ofhaphthionic acid.

Example 20.--The dye made by diaaotizing 2- naphthyla1nine-4,li-disulfonlc acid, coupling with meta-toluidine and treating theproduct with phosgene.

Example 21 .The dye made by tetrazotizing benzicline and coupling with 2mols of phenol p-sulfonlc acid.

Example 22.-The dye made by tetrazotizing d,e'-diarnino stilbenedisulionic acid, coupling with 2 mols of phenol and forming thedi-npropyl ether of the product.

Example 23.--The dye made by tetrazotizing e-,ddiarnino stilbenedisulfonic acid, coupling with 2 mole of phenol and forming the dibutylether of the product.

Example 2.-The dye made by tetrazotizing i,'diamino stilbene .disulfonicacid, coupling with 2 mole of 2,6-dimethyl phenol and forming thedi-n-propyl ether of the product.

The layers need not be colored complementary to their sensitivity,however, but may be colored alternatively with a dye that transmits thecolor for which the layer is mainly sensitive.

This film is exposed in a camera or under a suitable color positive ornegative. For example, it may be exposed to a natural color transparencyby a single exposure to tungsten light through suitable correctingfilters or by three simultaneous or successive exposures to lighttransmitted by red, green and blue filters in a suitable ratio of timesor intensities. It is then developed in an ordinary black and whitedeveloper, washed,

and fixed. The silver image is then reconverted to a sliver halide suchas silver chloride and the dyes are bleached by treatment in a sodiumstannite or sodium hydrosulfite bleach bath. This reduces the silverhalide image to metallic silver, and during the same operation, destroysthe dye in the region of the silver image so formed. The film is thenagain washed and the silver image is reconverted to silver halide in thesame solution previously used for this purpose or in any other suitablebath. The film is then fixed in hypo to remove the silver halide and iswashed and dried leaving pure dye images in the layers,

A specific method of treating a three-layer photographic elementaccording to my invention will now be described.

A multi-layer element having coated on a suitable support ared-sensitive layer containing Pontamine Fast Green BBL, a greensensitive layer containing the dye made by tetrazotizin 4.4 diamino2,2,5,5' tetramethyl triphenyl methane and coupling with 2 moles ofN-heptoyl "H-acid and a blue-sensitive layer containing the dipropylether of Brilliant Yellow (Color Index No. 364) is exposed to a naturalcolor transparency by a single exposure to tungsten light throughsuitable correcting filters. The element is then developed for abouteight minutes at 68 F in a tank of the following developer:

lvionomethyl-p-aminophenol The print is now placed for two minutes in astop bath consisting of: acetic acid, 28%, 505 cc; water, '4 liters.

The film is then thoroughly fixed in acid hypo of the followingcomposition:

Water (about 125 F.) c.c.. 50D Hypo "grams" 2'40 Sodium sulr'ite ...do15 Acetic acid (28%) c.c 48 Boric acid crystals grams 7.5 Potassium alum..do 15 Water to "liter-.. 1

The element is again washed and may then be hardened in a 1 to 20formalin solution, although this hardening step may be omitted if theemulsions have been suitably hardened before coatmg.

The silver images produced by the development are bleached to silverchloride by treatment for about ten minutes in the following solution:

Cupric chloride grams- Hydrochloric acid concentrated c.c 25 Water toliter 1 The film is then washed for about 5 minutes in several changesof distilled water. The dyes are then bleached by treatment for aboutfive minutes in a sodium stannite solution made in the following manner:

Stannous chloridegrams 8 Water (distilled) c.c 1G0 Sodium hydroxide (10%solution) do 100 The element is again washed first inplairr water forabout 30 seconds and then for 5 minutes in a solution of 20 0.0.concentrated hydrochloric in 1 liter of water. The silver images arethen bleached in the same copper chloride bath previously used. Thisreconverts to silver chloride the silver formed in the bleaching bath byreduction with the sodium stannite solution, to silver chloride. Thefilm is then again washed and is then fixed in an acid hypo bath of thesame composition as that previously used. It is then washed and dried,

In place-of the copper chloride bleach bath used to bleach the silverimages to silver chloride, baths of the following composition may beused:

A. Quinone, hydrochloric acid and ethyl alcohol.

B. Ferric chloride and hydrochloric acid.

0. Ammonium persulphate and hydrochloric acid.

In some cases it is desirable to add an organic solvent to the sodiumstannite bleach bath to reduce highlight stain. One volume of tertiarybutyl alcohol to about 10 volumes of the bleadh bath appears to be asatisfactory solvent for this purpose.

With certain dyes, Pontamine Fast Green 58L for example, a 2% solutionof sodium hydrosulfite can be used to bleach the dyes in the presence ofthe silver chloride image.

A photographic element containing the dyes reierred to above may beprocessed according to the method of the present invention to formcoloreduccessfully bleached by these aflected the dye in the remainingclaims.

I claim:

1. The method of forming a colored image in a photographic layercontaining a bleachable azo dye uniformly dispersed therein and arehalogenized silver image, which comprises bleaching the dye in theregion of said image with an alkaline stannous chloride bleach bath.

2. The method -'of forming a colored image in a photographic layercontaining a bleachable azo dye uniformly dispersed therein and arehalogenized silver image, which comprises bleaching the dye in theregion of said image with a sodium hydrosulflte bleach bath.

3. The method of forming a colored image in a photographic layercontaining a bleachable azo dye and unexposed silver halide uniformlydispersed therein, which comprises exposing and developing said layer,removing the unexposed silver halide without affecting the silver imageformed by development, reconverting the silver image to silver halide,and bleaching the dye inthe presence of. said image with alkalinestannous chloride to form a colorless dye compound and leave unportionsof the layer.

4. The method of forming a colored image in a photographic layercontaining a bleachable azo dye and unexposed silver halide uniformlydispersed therein, which comprises exposing and developing said layer,removing the unexposed silver halide without ailecting the silver imageforined by development, reconverting the silver.

image to silver halide, and bleaching the dye in the presence of saidimage with sodium hydrosulflte to form a colorless dye compound andleave unaffected the dye in the remaining portions of the layer.

5. The method of forming a colored image in a photographic layercontaining a bleachable azo dye and unexposed silver halide uniformlydispersed therein, which comprises exposing and developing said layer,removing the silver halide without aiiecting the silver image formed bydevelopment, reconverting the silver image to silver halide. andbleaching the dye in the presence of said image with a stannit oialkali-metal to form a colorless dye compound and leave unafiected thedye in the remaining portions of the layer.

6. The method of forming a colored image in a photographic layercontaining a bleachable aao dye and unexposed silver halide uniformlydispersed therein, which comprises exposing and developing said layer,removing the undeveloped silver halide without aflecting the silverimage formed by development, reconverting the silver image'to silverhalide, and bleaching the dye in an alkaline, reducing bleach bathcomprising an alkali metal salt of an acid selected from the groupconsisting oi stannous acid and hydrosulfurous acid and free of silverhalide developing agent in the presence of said image to form acolorless dye compound and leave unaffected the dye in the remainingportions of the layer.

GEORGE

